An air filter device of the type in question is disclosed in document WO 2005/082490 A1, for example.
Today, such known air filter devices are also increasingly used in modern automotive engineering in order both to qualitatively improve a fresh-air supply to a passenger compartment as well as to prevent an uncontrolled discharge of fuel vapours, for example in a tank ventilation region, into the environment. For this reason, such air filter devices customarily comprise a filter element that contains activated carbon, that is to say a hydrocarbon absorber. The activated carbon is arranged either packed in the filter housing of the air filter device as a bulk material or in a different manner and, in order to achieve the highest possible degree of filtration, is intended to be flowed through in as uniform a manner as possible. However, owing to so-called dead areas that that can be flowed through only minimally, if at all, this uniformity is not always possible.